Did you change anything on the truck when the mileage dropped, like tires (tire size or aggressive tread), or an accessory?
Was the differential oil changed, or still original? Old gear oil will get surprisignly thicker with age and drag more horsepower, especially on a 4WD.
Do you say "I love you" everyday? [img]smile.gif[/img]
Richard Lajoie
2001 GMC Savana 3500 SLE 6.5 TD - 15 passenger (the way to go with 7 children)
3" to 3.5" to 4" custom exhaust, 3.73 diff.
Amsoil 5W30 HDD, synthetic media oil filter
Amsoil air filter
1987 Suburban 6.2 test vehicule